with this method i would call the mainMenu function on a bank object in my main.cpp file and that mainMenu function would do all the output input and validation and then display the next menu. therefore my main function would probably look something like this

I suppose there are as many ways to design your program as there are people to program it. But if I were going to do it I would not put the menu in the Bank class at all but put it in the main() function.

You could also make a Menu class to encapsulate the banking operation. However, it might be better to specialize your Menu and give it a name (and make an 'abstract' base class Menu for general Menu's ).